Lock stitch sewing hook

ABSTRACT

A thread loop-taker in a sewing machine has a hook with a deep groove interrupting its outer surface and a spring bar bridging the opening at the base of the hook between the groove and the extension of the vertical side wall of the loop-taker.

United States Patent 11 1 Starnes Oct. 2, 1973 [54] LOCK STITCH SEWING HOOK 875,621 12/1907 Parkes .1 112/231 1 3 45 3 1 176] Invent? Siam, Norwood, 3 391,332 2/1363 111/2 5 3,386,401 6/1968 Johnson 112/231 x [22] Filed: g 1972 3,596,620 8/1971 Vogel 112/228 1 1 PP 279,530 I Primary Examiner-Alfred R. Guest Attorney-Henry N. Paul, Jr. et a1.

[52] US. Cl. ..112/231 151 1111. c1 D05b 57/14 1571 ABSTRACT [58] Field of Search 112/231, 228, 229, A thread loop-taker in a sewing machine has a hook 1 12/230 with a deep groove interrupting its outer surface and a spring bar bridging the opening at the base of the hook [56] References Cited between the groove and the extension of the vertical UNTED STATES PATENTS side wall of the loop-taker. 391,806 10/l888 Littlejohn \l2/23l 10 Claims, 5 Drawing Figures I I4 5 J & 6O

Pmmwmmm 3.762.350

PRIOR ART Fig. 1

LOCK STITCH SEWING IIOOK BACKGROUND OF THE INVENTION This invention relates generally to lock stitch sewing machines, and more particularly, to an improved looptaking reciprocating hook of the vertically-mounted type.

In the prior art sewing machines of the type known as lock stitch machines, a loop-taker is used to loop the upper thread around a stationary bobbin on which the under thread is wound. In such devices the bobbin case is carried in a bobbin case holder which in turn is carried by a loop-taker or hook.'See for example U. S. Pat. No. 391,806, dated Oct. 30, 1888, which 2hows 3he above mentioned parts and describes their operation in forming a lock stitch. In that patent, the loop-taker or hook is mounted on horizontal axis.

It is alsoknown to mount the loop-taker or hook on a vertical axis, as shown, for example, in U. S. Pat. No. l,931,456, dated-Oct. 17, 1933. A simplified perspective view of a prior art device is shown in FIG. 1 of the drawings of the present application It will be noted that the beak 18 or forward pointed portion of the hook has a beveled upper smooth I continuous surface which departs inwardly from the vertical sidewall 14. The lower surface 21 of the beak departs inwardly from aline contiguous with the line formed'by the departure of the upper surface of the side wall; said lower surface departing downwardly to a line formed by the inner edge of a groove 19 in the vertical side wall.

The advent of heavy denier synthetic filament thread has presented problems in the use of the standard lock stitch machine. For example, such thread tends to balloon slightly or lift away from the outer surface of the beak during the operation of the machine. In so doing it may become entangled with the bobbin case holder or may slip off the bottom of the beak and. get caught beneath the loop-taker. Either condition usually results in a broken thread requiring the machine to be stopped and repaired.

SUMMARY OF THE INVENTION The present invention overcomes these deficiencies in the prior art loop-taker or hook by providing a deep groove interrupting the continuity of the upper outer surface of the beak and a spring member at the base of the groove bridging the gapbetween the hook and the continuation of the side wall of the loop-taker, thereby preventing the thread from improperly moving off the surface of the loop forming device and overriding or underriding the device.

Accordingly, it's an object of this invention to provide a new and improved loop-taker of the type described wherein the thread is encouraged to take a thread line which will remain in engagement with the beak of the hook during the loop forming process.

Its another object of this invention to provide such a hook for use particularly with heavy denier synthetic filament thread.

These and other objects of the invention will become apparent from the following description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows a perspective view of a prior art device comprising a portion of a vertically mounted loop-taker having mounted therein 'a bobbin case holder;

FIG. 2 is a view similar to FIG. 1 of an improved device made in accordance with the present invention;

FIG. 3 is a side view on a slightly enlarged scale of the device shown in FIG. 2 which has been rotated several degrees and shows the device in operative relation to a needle and thread;

FIG. 4 is a partial top view on a greatly enlarged scale of the device shown in FIGS. 2 and 3; and

FIG. 5 is a'partial bottom view on a greatly enlarged scale of the device shown in FIGS. 2 and 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Although specific forms of the invention have been selected for illustration in the drawings, and the following description is drawn in specific terms for the purpose of describing these forms of the invention, this description is not intended to limit the scope of the invention which is defined in the appended claims.

A typical lock stitch sewing hook of the vertical axis type is shown in FIG. 1 designated generally 10 and comprises a base 12 formed with a substantially cylindrical side wall 14 extending around the greater portion of the base 12 to form a cup shaped member disposed at the end of a vertically positioned shaft 16. The other end of the shaft-(not shown) is'adapted to be engaged by the usual hook driving mechanism of a high speed vertical axis sewing machine. The prior art device as shown is provided with'the usual loop-seizing beak designated generally 18.

On modern devices, the base 12 is relieved as at 22. A tail or guard 24 is attached to the wall 14 and extends in overlapping relation to the point A of the beak 18, so that the under thread from the bobbin can not interfere with the loop thrown out by the needle.

I have used the same numbers to delineate the like parts in the structure disclosed in accordance with the present invention in FIGS. 2 through 5. The most significant changes are the provision of a deep groove designated generally 30 in the outer surface of the hook 10 and the provision of a spring bar 32 attached to the tail or the guard 24,-extending across the outer limits of the opening 22 and spring biased against the wall 14 at its free end. These changes prevent the loop of thread from overriding or underriding the hook beyond the beak portion 18, particularly when high denier synthetic filament thread is used.

As is well known in the prior art, the hook revolves to pass closely by the needle of the machine and pull out a partially formed loop of thread; expanding the thread upon the beak portion as the hook rotates. Thus the thread initially is looped about the point A of the beak 18 in FIG. 1 and as the device continues to rotate the thread is expanded about the beak until it reaches the groove 19. The dash line B represents a portion of the loop of thread which overlies the outer surface of the hook. The other portion of the loop is being drawn under the bobbin and is not shown in these figures. As the hook reciprocates backwardly the loop is drawn or cast off the free end of the beak l8 and in the course of this action passes completely over and around the spool or bobbin so that as the needle rises entirely out of the cloth, it takes'up the thread and draws the loop to complete the stitch. The action of the rotating hook is for all practical purposes an action of throwing the upper thread over the under thread, which is analogous to the passage of a shuttle through a loop. All this is well known in the art.

Referring to FIG. 3, a needle 40 is shown at some stage of its descent or retraction through the cloth toward or away from the rotating bobbin. The Figure merely illustrates the relative position of the rotating hook to the needle as it is well known in the art. The purpose of illustrating this in FIG. 3 is merely to show, as illustrated by the dash line C that a degree of tension is maintained in the thread so that the thread is drawn into the groove 30.

In the prior art devices, (See FIG. 1 of U.S. Pat. No. l,93l,456) a beveled upper surface departs from the side wall 14 inwardly to the upper terminal end of the rotating hook. This surface 15 extends continuously and uninterruptedly while narrowing to the point A of the beak 18. The line 17 FIG. 1 which represents the intersection between the beveled lower surface 21 and the beveled surface 15. Surface 21 departs from this line inwardly toward the base 12 of the hook; broadening from the point A" at the end of the beak 18 to the inner edge 25 of the groove 19. The lower edge 23 of the beak 18 and surface 21, terminates at the base 12 within the relieved portion 22. The groove 19 extends inwardly from the wall 14 and increases in depth from its point of intersection with the beveled surface 15 to its terminus at the base 12. The line of intersection 25 between the surface of the groove'19 and the surface 21 of the beak defines both the inner limit of the groove and the extent of the beak.

In accordance with the present invention the beak 18 is modified as shown in FIGS. 2 through 5. The groove 19 shown in FIG. 1 which defines the limit of the beak is replaced with a groove 30 which extends from its lower limit at the base 12 in the opening 22 completely to the top or upper periphery of the beveled surface 15. Surface 15 is, therefore, interrupted by the groove 30 and is no longer continuous. The surface 115 continues in like manner to the surface 15 FIG. 1 on the other side of the groove 30 to the point A.

The lower beveled surface 21 is likewise interrupted by the groove 30. For purposes of delineating the structure clearly, I have emphasized the edges 50, 52, and 54. It should be borne in mind that these are slightly rounded and smooth rather than sharp. The beveled surface 58 which forms the groove 30 extends inwardly to the line 60 which is the intersection of this surface with a surface 56. The surface 58 lies in a plane on an angle to the axis of the device, as shown in FIG. 3. The newly formed surface 56 extends from this line of deepest penetration outwardly and generally triangularly to intersect the surface 115 at line 50 and the surface 121 at line 52. The surface 12], therefore, does not extend completely to the full depth of the groove, as did the surface 21 in the prior art. The remainder of the surface 121 is, however, the same as the surface 21 of the prior art.

The effect of this portion of the invention is that the outer portion of the loop thread C" will not normally override the beveled surface 15. It will, therefore, re main properly hooked until it is cast off by the action of the device.

To prevent the bottom portion of the loop of thread from underriding the device and becoming entangled beneath the base 12 of the hook 10, l have provided a spring loaded bar 32 in the form of a cylindrical rod or wire welded or brazed or otherwise suitably attached at one end 33 to the tail or guard 24. The bar 32 is slender and arcuately formed and biased by its own resilience, so that its free end 34 lays against the vertical wall 14 and exerts a force thereon. Thus while a thread could be drawn between the free end 34 and the wall 14, it would take more than the normal tension force applied to the thread in the making and throwing of a loop in a sewing machine. The bar 32 is positioned most preferably at the outer terminus of the lower edge of the groove 30, thus preventing the outer portion of the loop of thread C from sliding beneath the base 12. The device works on a single loop, and indeed, only one portion of that loop; that being the portion engaging the outer surface of the hook. The upper deep groove interrupting the continuity of beveled surface 15 together with the slightly convex surface 56 prevents the upper portion of the thread loop from overriding, while the bar 32 prevents the bottom portion of the thread from slipping off and under the device.

It will be understood that various changes in the details, materials and arrangement of parts which have been herein described and illustrated in order to explain the nature of this invention, may be' made by those skilled in the art within the principle and scope of the invention as expressed in the following claims.

It will further be understood that the Abstract of the Disclosure set forth above is intended to provide a non-legal technical statement of the contents of the disclosure in compliance with the Rules of Practice of the U.S. Patent Office, and is not intendedto limit the scope of the invention described and claimed herein.

What is claimed is:

1. In combination with a sewing machine having a hook for taking a thread loop from a needle, said hook being disposed on the end of a shaft and comprising a base and a side wall extending axially from said base, the improvement comprising: a beak forming the free end of the hook for looping the thread off the needle, said beak comprising a surface which is beveled from the side of the hook inwardly toward the periphery thereof remote from the base; a second surface intersecting said first surface which is beveled inwardly toward the base of the hook; and a groove interrupting the continuity of said first surface.

2. The invention of claim 1' wherein said groove limits the extent of the second surface.

3. The invention of claim 1 wherein said groove extends from the periphery of said first surface completely across said first and second surfaces. 7

4. The invention of claim 3 wherein said groove extends to the base of said hook.

5. The invention of claim 4 wherein said groove extends inwardly to its deepest penetration at said base.

6. The invention of claim 1 wherein said groove comprises a plurality of surfaces one of which lies in a plane at an angle to the axis of the hook and the other of which intersects said first and second surfaces.

7. In the invention of claim 1 wherein the base of said hook is relieved and the wall of said hook extends substantially cylindrically around said base to the limits of the relieved portion of said base; and a tail is attached to the wall and extends beyond the relieved portion toward the opposite end of the wall; and said beak extends from said opposite of the wall toward and in overlying relation to said tail, the arrangement providing a space therebetween, the improvement comprising: a

6 bar engaging said tail and said wall, extending across tends to said base. said space between said tail and said wall. 10. The invention of claim 8 wherein said bar is 8. The invention of claim 7 wherein said bar is posifixedly attached at one end and spring biased at the tioned at said base. other in its engagement with said tail and said wall.

9. The invention of claim 8 wherein said groove ex- 5 UNITED STATES PATENT OFFICE v v CERTIFICATE OF CORRECTION Patent No. 3,762,350 D t d October 2, 1973" I Invent r( R. Starnes It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: i v LI On the general information page, after item [76] insert Collins, & Aikman Corporation "[73] Assignee:

' v New York, New York- Signed fiq s ealeq this 5t day or March 197R.

(SEAL) Attest;

EDWARD M.FLETCHER, JR. 0. MARSHALL DANN Attesting Officer I Commissioner' of Patents uscoMM-oc cone-poo F ORM PO-IOSO' 10-69) 

1. In combination with a sewing machine having a hook for taking a thread loop from a needle, said hook being disposed on the end of a shaft and comprising a base and a side wall extending axially from said base, the improvement comprising: a beak forming the free end of the hook for looping the thread off the needle, said beak comprising a surface which is beveled from the side of the hook inwardly toward the periphery thereof remote from the base; a second surface intersecting said first surface which is beveled inwardly toward the base of the hook; and a groove interrupting the continuity of said first surface.
 2. The invention of claim 1 wherein said groove limits the extent of the second surface.
 3. The invention of claim 1 wherein said groove extends from the periphery of said first surface completely across said first and second surfaces.
 4. The invention of claim 3 wherein said groove extends to the base of said hook.
 5. The invention of claim 4 wherein said groove extends inwardly to its deepest penetration at said base.
 6. The invention of claim 1 wherein said groove comprises a plurality of surfaces one of which lies in a plane at an angle to the axis of the hook and the other of which intersects said first and second surfaces.
 7. In the invention of claim 1 wherein the base of said hook is relieved and the wall of said hook extends substantially cylindrically around said base to the limits of the relieved portion of said base; and a tail is attached to the wall and extends beyond the relieved portion toward the opposite end of the wall; and said beak extends from said opposite of the wall toward and in overlying relation to said tail, the arrangement providing a space therebetween, the improvement comprising: a bar engaging said tail and said wall, extending across said space between said tail and said wall.
 8. The invention of claim 7 wherein said bar is positioned at said base.
 9. The invention of claim 8 wherein said groove extends to said base.
 10. The invention of claim 8 wherein said bar is fixedly attached at one end and spring biased at the other in its engagement with said tail and said wall. 